Microsatellites for cultivar identification in Pelargonium

We have isolated and characterised microsatellite loci from Pelargonium sp. to explore the potential of these markers for cultivar identification. Sma ll-insert libraries from a zonal (Pelargonium x hortorum cv. Isabell) and a n ivy-leaved variety (P. peltatum cv. Guenievre gergue) were enriched for d (AG), d(AC), d(CAA), d(GAA) and d(GATA) repeats. Of 141 positive clones seq uenced, 133 contained a microsatellite. Primers for PCR amplification were designed to the flanking regions of 57 microsatellites, resulting in interp retable amplification products of the expected size for 29 loci. Seventeen primer pairs amplifying 18 loci were used to fingerprint 44 di- and tetra-p loid Pelargonium accessions representative of commercially available variet ies. Multilocus genotypes obtained at 3 loci distinguished among all access ions, except for three known flower colour sports and a fourth, phenotypica lly very similar, variety. Allelic composition was also identical within tw o other sport 'families' typed at the same 18 loci. UPGMA and principal co- ordinate analysis of pairwise distance matrices derived from PCR amplificat ion patterns revealed four distinct assemblages. The first group consisted of tetraploid P. x hortorum varieties, a second group contained diploid P. x hortorum, a third, tetraploid P. peltatum accessions, while a fourth, ver y distinct, group consisted solely of diploid P. peltatum varieties. Polymo rphism in P. peltatum was equal or greater than in P. x hortorum at 17 of t he 18 loci, indicating that the analysed P. peltatum varieties form a genet ically more variable array.